Whales make new friends as warmer seas drive migration

IN AUGUST 2010, a bowhead whale from the Bering Sea swam into the North-West Passage. Having negotiated Alaska and picked its way through the maze of ice-ridden channels off the north coast of Canada, it made its way to Viscount Melville sound. There it met a second bowhead, which had entered the passage from Baffin bay, next to Greenland.

The two met because the passage, long blocked by ice, is opening as the climate warms. The anecdote, which came to light thanks to satellite transmitters on the whales, is part of increasing data showing how ocean life is being transformed by rising sea temperatures, with some bits of apparently good news to sweeten the pill.

It's not just whales that are affected by warming seas (see map). Steve Simpson at the University of Bristol, UK, looked at 25,612 trawls in fisheries around the UK and in the North Sea between 1980 and 2008. There waters have warmed by 0.05 °C a year since 1980.Populations grew for 27 of the 50 most common fish; nine declined and 14 held steady (Current Biology, DOI: 10.1016/j.cub.2011.08.016). "I had expected to see many struggling and maybe one or two doing well," he says

In his surveys, cold-adapted species like cod were all in decline, replaced by warm-adapted ones like red gurnard, which breed faster. Markets are catching on. "Five years ago fishermen were selling red gurnard as bait to crab fishermen for 50 pence a fish," Simpson says. Now restaurants buy them for £5 a fish.

But the pill is bitter-sweet. An open North-West Passage may be good news for bowheads, which will have more places to feed, but many Inuit will struggle, since they rely on walruses that are running out of sea ice on which to breed. And although UK fish markets may be boosted, that's no help to fishing communities in the tropics. If temperatures rise dramatically, many species there will either move out or die.

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